The present invention relates to a coffee maker and, more particularly to a control apparatus for a coffee maker with a detecting circuit for detecting on and off states of a main switch for a mill mechanism, a thermal switch for regulating temperature of a heating unit in a drip mechanism and a heater switch of the heating unit.
For a better understanding of the present invention, the conventional combination type coffee maker will be briefly described. The combination type coffee maker to which the invention may be applied is provided with a mill mechanism and a drip mechanism as disclosed in U.S. Pat. No. 4,196,658 issued to Takagi et al on Apr. 8, 1980, which is assigned to the same assignee as of the present application. In the mill mechanism, a cutter is provided in a case containing coffee beans and is driven by a motor to mill coffee beans into coffee powder. The drip mechanism pours hot water into the coffee powder in the case to make coffee. A heating unit for boiling water and keeping coffee warm is installed in the drip mechanism and contains a heater. Some mill mechanisms for the conventional coffee maker employ a spring-driven timer for setting a drive time of the motor. It is desirable to set the drive time, or the milling time so accurate that the coffee maker may serve coffee with preferable density. The case has a cover for preventing coffee beans from scattering outside the case when the coffee beans are milled. To this end, a cover switch is used for shutting off the current path to the motor for driving the cutter, when the cover is open. In addition, the conventional coffee maker is provided with a thermal switch which turns off when the temperature of the heating unit exceeds a predetermined value, and a heater switch for controlling on and off of the heater. The on and off states of the cover switch, the thermal switch, and the heater control switch must be detected for automatically operating the control apparatus for the coffee maker. To realize this end, an approach might be allowed in which the on and off states of these switches are indivisually controlled. However, this approach makes the control apparatus extremely complicated and hence is unpractical.